New catalysts for formic acid fuel cells

Abstract

Thallium adatoms deposited at under-potentials have shown the catalytic effect during the electrooxidation of formic acid on platinum ruthenium alloys. At Pt/Ru with an optimal coverage degree with adatoms Tl, HCOOH is oxidized at nearly 180 mV more negative potential than at Pt/Ru electrodes. The catalytic effect of modified Pt/Ru electrodes is plausibly caused by interaction of the Tl adatoms, located at Pt atoms with OH species of adjacent Ru atoms. These interactions stabilize Ru-OH species and allows for their formation at more negative potentials than at the Pt/Ru electrodes. The Ru-OH species oxidize firmly bound intermediates COad and thus release the Pt atoms for the oxidation of subsequent HCOOH molecules. The catalytic effect is probably caused by the third-body effect.

Keywords

• formic acid
• thallium
• catalyst
• electrochemistry
• bifunctional mechanism